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Research

Optical Imaging

Detection, grading and delineation of articular cartilage degeneration and injuries from arthroscopic
images have been considered inaccurate and poorly repeatable because the diagnosis is based on
visual evaluation only [1, 2].

Optical coherence tomography (OCT) is a promising technique for detection, delineation and
quantitative assessment of cartilage lesions [3]. It is an interferometer based optical imaging
technique where reflected and backscattered near-infrared light from different depths is measured.
Light reflection and scattering properties of a tissue are related to tissue structure and composition.[4]

We study optical coherence tomography in articular cartilage imaging. OCT provides high spatial
resolution (up to 10 Ám) and is ideally suited for both visual assessment of cartilage lesions and
quantitation of surface roughness [5, 6]. Unlike conventional arthroscopy technique, OCT also
enables detection of subsurface lesions (Fig. 1) and measurement of cartilage thickness [7] (Fig. 2).
Furthermore, quantitative reflection and backscattering analysis can be performed [5, 8]. Our aim is
to study how articular cartilage degeneration and injuries affect the light reflection and scattering
properties of the cartilage and how the state of the cartilage could be assessed repeatably and
reliably from quantitative optical information. Miniaturized OCT probes enable arthroscopic OCT
imaging in vivo and development of multimodality imaging techniques.

Figure 1. Subsurface cartilage lesions unvisible in the conventional arthroscopic image can be detected with OCT.

Figure 2. Lesion size and cartilage thickness can be measured from the OCT image. Near-infrared light can penetrate 1-2 mm into the cartilage tissue.